class Solution {
public:
    vector<vector<int>> fourSum(vector<int>& nums, int target) {
        vector<vector<int>> ret;
        sort(nums.begin(),nums.end());

        int n = nums.size();
        for(int i = 0;i < n;)
        {
            for(int j = i+1;j < n;)
            {
                int left = j + 1;
                int right = n-1;
                long long aim = (long long)target - nums[i] - nums[j];
                while(left < right)
                {
                    int sum = nums[left] + nums[right];
                    if(sum < aim) left++;
                    else if(sum > aim) right--;
                    else
                    {
                    ret.push_back({nums[i],nums[j],nums[left],nums[right]});
                    left++;right--;
                    while(left < right && nums[left] == nums[left-1]) left++;
                    while(left < right && nums[right] == nums[right+1]) right--;
                    }
                }
                j++;
                while(j < n && nums[j] == nums[j-1]) j++;

            }
            
                i++;
                while(i < n && nums[i] == nums[i-1]) i++;
        }
        return ret;
    }
};